This project seeks to determine the solid-state conformation of polysaccharides from the surface of bacterial cells. Current interest centers on the conformational similarity of the disaccharide beta-D-Glucuronic acid (1 yields 4) beta-D-glucose which is a consitituent of both types 3 and 8 pneumococcal capsular polysaccharide. X-ray diffraction and computer-aided modeling with the LALS algorithm are being used to determine the structure of these and other capsular polysaccharides. Since these molecules are polyanions, the effect of various cations on the conformation is also an important consideration which is being investigated.